An illuminating push button switch is a type of switch which has been widely used in products around our life. It simply indicates whether a device is switched on/off or which floor the elevator will stop by the illumination of a light source incorporated within the switch. A conventional illuminating push button switch as shown in the FIG. 9 discloses a push button arrangement on circuit board e.g. for production mixer in television studios, having light source encompassed by a push button with transparent top. Said switch consists essentially of a base (7) for accommodating a light source (70) and a cap portion (8). A light guiding element (71) is provided at the center of the base (7) to project the light upwardly and a transparent plate (72) is disposed onto said light guiding element (71) for reflecting the light. Two metal elements (73, 74) are provided about the periphery of the light guiding element (71). Said cap portion (8) comprises of a transparent cover (82) and a frame (81). A transparent film (83), printed with figures or characters, is provided at the bottom of the cover (82). The illumination is provided by connecting electrically the light source (70) (e.g. LED) to a printed circuit board (PCB) (9). For further information regarding the structure of the traditional illuminating push button switch, please refer to the cited document DE 10044077A, entitled “Die folgenden Angaben sind den von Anmelder eingereichten Unterlagen entnommen”.
Said push button switch as disclosed in FIG. 9 or cited reference owns following drawbacks:    1. The assembling methods initiates by connecting the light source (70) to the PCB (9). Afterward, the push button switch assembly is further engaged with the PCB (9) and receives the light source (70) within. The two steps assembling method complicates the installation as for the maintenance either. Further, the base of the switch has a complex structure; the installations and assembling of the light guiding element (71), said metal elements (73, 74), springs and frame (81) require specific tool and special training, increasing the manufacture cost and difficulty of the maintenance. Therefore, to provide a push button switch with simple structure for simplifying the assembling or repairing method has become the primary objective of the present invention.    2. As disclosed previously, said base (7) is made of transparent material, and the light guiding element (71) is against the light source. Thus, when the light source (70) is fastened onto the PCB (9) by welding or gluing, the solder or glue may be transferred to the light guiding element (71) and lower the effect thereof. Thus, to prevent the illumination affect by the fastening means has become another objective of the present invention.    3. The light source (70) is further engaged with said light guiding element (71) by gluing. Besides than reducing lighting effect as disclosed previously, it troubles the replacement of the light source (70). Thus, finding an easy and simple way to install the light source without damaging both light source and switch structure has become another objective of the present invention.    4. Since the light is emitting upwardly, the plate (72) is provided to diffuse partial of light emission toward the sides. However, it reduces the light which can be seen from the cap (8). Therefore, to ensure that light is bright and visible from the cap (8) is also an objective for the present invention.